1. Field of the Invention
The present invention relates to a substrate connecting structure between a plurality of signal lines inserted into a signal cable and a substrate to which the signal lines are electrically connected.
2. Description of the Related Art
Endoscopes are used in medical fields, industrial fields, and the like. The endoscopes include a so-called electronic endoscope, which incorporates an image pickup apparatus in a distal end portion of an insertion portion. There is a demand for electronic endoscopes for improving the quality of images, and thus high-resolution image pickup devices have been developed.
In an endoscope, a signal transmission channel, connecting an image pickup apparatus incorporated in the distal end portion of an insertion portion and an external device such as a video processor, has a long length. Additionally, in the insertion portion of the endoscope and the operation portion of the endoscope, a signal cable is inserted, as well as many endoscope built-in items such as a light guide fiber bundle that supplies illumination light, an air feeding tube forming an air feeding conduit, a water feeding tube forming a water feeding conduit, a multi-purpose tube serving both a suction conduit and a treatment instrument conduit, and a bending wire that brings a bending portion into bending action.
As to an electronic endoscope apparatus, it is possible to achieve the improvement of image quality and the reduction of the size of a signal cable to be inserted into an insertion portion by providing a relay circuit substrate that amplifies drive signals for an image pickup device in the operation portion of the endoscope. For example, Japanese Patent Application Laid-Open Publication No. 2009-279148 discloses an electronic endoscope apparatus that prevents itself from being increased in size, in particular prevents an insertion portion from being increased in diameter even when an image pickup apparatus capable of acquiring high-quality images is disposed in the distal end portion of the insertion portion.
The relay circuit substrate provided in the operation portion of the endoscope is configured to have a small size. In addition, a substrate-to-substrate connector to be detachably connected to the relay circuit substrate is also configured to have a small size. The substrate-to-substrate connector is provided in the end portion of a signal cable extended from the image pickup apparatus.
The substrate-to-substrate connector and the signal cable is inserted from one end side of the insertion portion, drawn out from the other end side, led into the operation portion, and connected to the relay circuit substrate. For this reason, it is desired to make a width dimension and a thickness dimension, which is the outside shape of the substrate-to-substrate connector as small as possible to allow the substrate-to-substrate connector to pass through the insertion portion smoothly. In addition, it is desired to design a configuration that prevents a break or the like from occurring owing to loads imposed on a joining portion between a signal line and the substrate in inserting work or in connector connecting/disconnecting work.
For example, Japanese Patent Application Laid-Open Publication No. 2012-221586 discloses a cable fixture that enables fixing a plurality of cables on the edge portion of a printed circuit substrate and positioning the plurality of cables with good precision and allows soldering the cables to a connecting pad of the printed circuit substrate to be performed easily with good workability.